A mere 1,4 seconds… Out in the world, that isn't a great deal of time. We waste so many hours on social media posts and silly text messages that we don't even consider 1,4 seconds.
But out on a racetrack that small increment is a relative eternity. Formula One teams would sell their families to make up that sort of time over their nearest rivals, but that is exactly the gain I experienced recently.
A quantum leap
At the most recent race meeting, I completed a lap of Killarney in 1 min 37,01, a time that was 1,4 seconds quicker than I had managed to date. As much as I'd like to take full credit for that huge gain there were other forces at play.
Standard fare
If you've followed the progress of Project MX-5 to date you will know that the car has been race-prepared/modified in several areas. Most notable among these is the full roll-cage, semi-slick rubber and racing safety gear (seat/harness).
Under the bonnet, however, there has been very little revision. In essence, the changes comprise an exhaust system (not a branch) and the fitment of a K&N high-performance air filter. That's it.
Of course, any road-racer/tuner will tell you that to go faster you need more power. Until now, I have been concentrating on the safety aspects and driving enjoyment rather than outright speed.
Conservative approach
But most of the cars that I race against in the Kent Homes Fine Cars series are not standard and more often than not I end up without anyone to race against, except the clock. Well, I finally decided to do something about it.
The 1,6-litre inline four-pot in my MX-5 was developed in the mid-1980s, which means that it's far from high-tech. There is no variable valve-timing or lift system at play. In 1989, Mazda set up this engine to run on 90 RON petrol, so there was definitely room for improvement.
However, the standard fuel injection system wouldn't be too easy to manipulate to make any significant gains in power.
Power up
I scouted around for locally made, standalone management systems and stumbled upon PowerMods. Owner of the firm is the well-known Domingos de Carvalho, who was quite open to the idea of getting involved with Project MX-5.
PowerMods provided the ECU along with the wiring harness and recommended we use local tuning firm 1st Performance as it has the most experience installing and tuning PowerMods systems in Cape Town.
I was happy to enlist their services as 1st Performance is well-known and trusted and tunes several dozen local drag and racecars that I know of, and countless modified road cars, too.
I contacted 1st Performance and co-owner Bradley van Rooi agreed to help out. First order of business was to do a baseline dyno run that we would later use for comparison purposes. As is, the engine produced 67 kW @ 6 800 r/min on the wheels.
Plumbed, wired and ready to go
Van Rooi and partner Craig Fletcher installed the ECU, which was no easy task as several inputs to the system were not accounted for from the original computer box of the car. With several days of cutting, wiring, soldering and, no doubt, scuffed knuckles, the PowerMods ECU was ready to go.
After a few teething issues, the system eventually ran, though it wasn't smooth or making loads of extra power, but that would come in time.
Fine-tuning
Once he was happy that the ECU was interacting with the car, Fletcher set about tuning the ignition timing and fuelling. The PowerMods ECU can do so much more, including launch control, data logging, anti-lag, boost control, etc. but my car has no need for any of that functionality. Going forward, though… who knows?
Initial dyno runs showed a gain of 6 kW, a handy 10% over where we started. We soon realised that the restrictive air-flow meter (AFM) could also be removed as the ECU only required manifold pressure (via a MAP sensor) as an input.
Custom bits
We had a custom intake fabricated that did away with the old-style AFM and expected power as well as throttle response to improve.
Back on the dyno, Fletcher set to work with his trusty laptop. Finely adjusting timing and fuelling he eventually found a sweet spot, delivering smooth power across the engine range.
When the final runs were done, the peak power figure went up to 77 kW @ 7 200 r/min, which represented a 10 kW gain. You can watch the final dyno run in the video at the bottom of this post.
We gave the car a minor service between races with a service kit supplied by M-Trak Performance, which included NGK-R spark plugs, Pertamina Fastron full synthetic oil and an oil filter. The reward for all the tuning and fresh parts was the lap time I quoted above.
More to come
I was extremely happy with the gains, as were Fletcher and Van Rooi, but as with these projects the road is never-ending. Fletcher is sure that he can eke a few more horses from the motor with further tuning, and Van Rooi is adamant that I should start shopping for aftermarket camshafts and Vernier gears if I want to see real power gains.
The latter route is one I am seriously starting to consider…
Reader feedback
As usual, all comments and suggestions are welcome. I look forward to hearing from you. For intermediate updates feel free to follow the Project MX-5 facebook page.
Here are links to all the previous Project MX-5 posts:
Part 11: http://www.carmag.co.za/speed_post/project-mx-5-part-11-race-weekend-5-quicker-than-ever/
Part 10: http://www.carmag.co.za/speed_post/project-mx-5-part-10-race-weekend-4-wrong-way/
Part 9: http://www.carmag.co.za/speed_post/project-mx-5-part-9-race-weekend-3/
Part 8: http://www.carmag.co.za/speed_post/999241389/
Part 7: http://www.carmag.co.za/speed_post/project-mx-5-part-7-race-weekend-2/
Part 6b: http://www.carmag.co.za/speed_post/project-mx-5-part-6b-race-debut/
Part 6a: http://www.carmag.co.za/speed_post/project-mx-5-part-6-race-ready-in-record-time-part-a/
Part 5: http://www.carmag.co.za/speed_post/project-mx-5-part-5-shiny-and-new/
Part 4: http://www.carmag.co.za/speed_post/project-mx-5-part-4-breathe-in-and-out/
Part 3: http://www.carmag.co.za/speed_post/project-mx-5-part-3-racetrack-debut/
Part 2: http://www.carmag.co.za/speed_post/project-mazda-mx-5-part-2/
Part 1: http://www.carmag.co.za/speed_post/project-mx-5-part-1/
The post Project MX-5: Part 12 (Tuning for speed) appeared first on CARmag.co.za.